What does 惰性 mean?
惰性 is a Japanese noun meaning “inertia, force of habit” in English. It can also be translated as “inertia” depending on context. It is written as 惰性 in kanji, だせい in hiragana, and dasei in romaji. This word is part of JLPT N1 vocabulary.
Example sentence
高校時代からつきあっている彼氏はいるものの、つきあいが惰性になっていると感じ、不満をつのらせている。
She has a boyfriend she's been going out with since high school but feels their relationship has become a matter of habit and is increasingly dissatisfied.